An ecommerce team needs to be alerted when an Amazon EC2 instance's CPU utilization rises above 80% during a sales event. Which solution will meet this requirement?

The correct solution is to create a CloudWatch alarm because Amazon CloudWatch is the monitoring service that collects and processes raw data from AWS services like EC2 into readable, near real-time metrics. CloudWatch alarms can be configured to watch these metrics (like CPUUtilization) and initiate actions, such as publishing a notification to an Amazon SNS topic, when a threshold (e.g., 80%) is breached. CloudTrail records API calls and events for auditing, not real-time metric monitoring, so a CloudTrail alarm is incorrect. Running a cron job on the EC2 host is a manual and less scalable approach compared to CloudWatch's integrated monitoring capabilities. A Lambda function querying CloudTrail for CPUUtilization is also incorrect because CloudTrail does not store performance metrics; CloudWatch does.